In modern crinoids respiratory gas uptake occurs through the thin walled tube feet on the arms. Perhaps for this reason crinoids generally required no specialized respiratory structures. In contrast, the blastozoans, which had greatly reduced or lost the tube feet generally, possessed complex respiratory structures to improve gas exchange. Thus, the callocystitids had three pairs of rhomb-shaped areas called pore rhombs, each with slots leading to thin walled calcite tubes that extended into the theca. Presumably these allowed seawater to come into contact with the cystoid's body wall in a large surface area. Likewise, Stephanocrinus had u-shaped pore canal systems that extended into their thin walled coronal crests (Brett et al., 1983). These structures were also probably canals for gas exchange.

Development of columns in most crinoids and cystoids enabled their feeding and respiratory structures, at least in adults, to be elevated into currents strong enough to permit feeding. Even the the undescribed Rhenopyrgid edrioasteroid (Figures 237 - 242) developed a turreted theca to elevate feeding surfaces several millimeters above the substrate.

Certain short-stalked crinoids, such as Gazacrinus and the cystoid Callocystites, must have fed from an intermediate position elevated a few centimeters above the seafloor. Others, such as Macrostylocrinus, Eucalyptocrinites and the cystoid Caryocrinites (Figures 288, 277 and 311) apparently fed from a level as much as 20 cm above the seabed. Still others, notably the slender armed Dendrocrinus and some Dimerocrinites (Figures 269 and 294) had a much more elevated feeding strategy with columns occasionally running as much as 50 cm long. These crinoids were especially adapted to elevating the crown as rapidly as possible above the inhospitable mud bottom. Not surprisingly, these crinoids are occasionally found in large numbers in units such as the upper Rochester Shale (Burleigh Hill Member) where other echinoderms are never found. These were opportunistic crinoids that could survive and even thrive in settings inimical to most benthic life and their elevated strategy together with relatively flexible attachment strategies at least for the dendrocrinids (which had whorled cirri on the distal stem; Figures 272 and 275) were surely important for this mode of life.

Surprisingly, however, certain crinoids reversed the trend of feeding above the substrate and fed close to the seafloor. For example, the calceocrinids ("slipper crinoids"), such as Catatonocrinus halli apparently had a recumbent column that lay upon the seafloor; their crowns were hinged on the basal plates and could be folded down against the column. This was very likely a defensive strategy for an organism that lived close to the seafloor. In particular, during times of storm current stirring of mud the feeding surfaces of the arm could be shut down rather effectively.

In an analogous way, Crinobrachiatus lived close to the substrate with a coiled column and stout cirri that not only aided in anchoring the crinoid in the substrate but also enshrouded the delicate crown when the animals withdrew the crown into the coils of the stem. We reconstruct this crinoid as having lived with the stem oriented parallel to the substrate and propped up by the stiff, branching cirri, which are progressively longer from the posterior tip forward (Eckert and Brett, 1988).

Gastropods had varied modes of life. Most were active organisms that utilized a muscular foot to crawl on the seabed and a rasping tongue or radula for feeding. Some of the more typical platyceratids in the Rochester assemblages, such as Naticonema may have lived as active benthic scavengers or predators. However, the majority of this group was adapted to an unusual mode of life. These organisms attached, probably as juveniles, to the tegmens of certain crinoids (Figures 461 - 463), especially Macrostylocrinus, Dimerocrinites and Lyriocrinus and the cystoid Caryocrinites, and lived a dependent, sedentary life attached to their hosts. These gastropods were positioned over the anal vents of the echinoderms where they apparently fed upon fecal material expelled by their hosts; that is, they were coprophagous. They have generally been interpreted as commensals that benefitted from their hosts but did them little or no harm. However, some authors have argued that these snails could also be parasitic. At least by the Devonian there is evidence that some platyceratids used their radulas to drill into the gut of their hosts and rob them of some food (Baumiller and Gahn, 2002).